Search NASA⌕ Search

SEARCH · Search NASA

Results for “effective turbulence”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

Panel and open conference discussions

Aircraft design and atmospheric turbulence effects on sonic boom generation and overpressure prediction methods using flight test data

Source record↗
NASA NTRS1971

Sonic boom

Sonic boom phenomena, discussing supersonic flow near aircraft, atmospheric propagation, distortion, focusing, caustics, turbulence effects and reduction

Hayes, W. D.↗
NASA NTRS1971

A model for analysis of the temperature field downstream of a heated jet injected into an isothermal crossflow at an angle of 90 deg

The temperature distribution downstream of a heated jet entering an isothermal crossflow at an angle of 90 deg is predicted using two conduction models with energy sources above the point of injection, in one case a point source and in the second a line source. The models use effective turbulent diffusivities that are determined empirically from previous measurements. Temperatures predicted by the models are compared to experimental results.

Eriksen, V. L.↗
NASA NTRS1973

Calculation of transitional boundary-layer flows.

The results of a finite-difference calculation of hypersonic transitional boundary-layer flow are presented. Precursor-transition and low Reynolds number turbulence effects are included. These calculation results are compared with data from a source where profiles are available at the beginning, middle and end of the hypersonic transitional flow. The results indicate that the low Reynolds number effect is the most important.

Bushnell, D. M.↗
NASA NTRS1975

Wind modeling and lateral control for automatic landing

For the purposes of aircraft control system design and analysis, the wind can be characterized by a mean component which varies with height and by turbulent components which are described by the von Karman correlation model. The aircraft aero-dynamic forces and moments depend linearly on uniform and gradient gust components obtained by averaging over the aircraft's length and span. The correlations of the averaged components are then approximated by the outputs of linear shaping filters forced by white noise. The resulting model of the crosswind shear and turbulence effects is used in the design of a lateral control system for the automatic landing of a DC-8 aircraft.

Holley, W. E.↗
NASA NTRS1974

Balloon borne laser transceiver

A balloon borne laser transceiver (BBLT) which was carried to an altitude of 80,000 feet, was used to measure the turbulence effect of the atmosphere in daylight on laser beams going both up and down through the intervening atmosphere. The principles of operation of the BBLT are discussed. The instrument must acquire an up-going argon laser beam, lock onto it, and transmit back to the ground observatory a helium-neon laser beam. Questions of system operation for the down-going and the up-going beam are considered along with a servo system analysis.

Wischnia, H. F.↗
NASA NTRS1976

A turbulence model for nonequilibrium adverse pressure gradient flows

This paper presents a method for calculating compressible adverse pressure gradient boundary layers by using an algebraic eddy viscosity turbulence model that has been modified for variable pressure gradient and turbulence memory effects. The pressure gradient corrections are based on previous incompressible data correlations. Several methods for including the effects of turbulence memory are evaluated. A new lag model, which gives good agreement with available experimental data, is developed. Finally, a correlation is developed for the lag length parameter employed in the model as a function of the known experimental flow variables.

Horstman, C. C.↗